The reason the calls drop in your home is because of the MHz on the phone. It is easier to talk on a t-mobile phone in walmart than it is to talk on a sprint phone in walmart. Its due to the system and motherboard of the phone. When they made cell phones they did not know people would have steel rods and brick building. When you look at a coverage map it shows the coverage for the area around your home, not inside. They will tell you that cell phones are meant to be mobile and not used as a home phone.